In order to achieve as complete afterburning as possible of the injurious constituents of exhaust gases of internal combustion engines, and to obtain an effective reaction in the combustion chamber of such a reactor, thorough mingling of the exhaust with the secondary air supplied and a sufficiently long reaction zone with low flow resistance are required. However, especially with the limited space generally available to accommodate a reactor, these requirements are not so easily satisfied.
In one known embodiment of a reactor (Public Disclosure No. 1,300,129), the reactor chamber has been divided, by means of a partition having a central hole, into a combustion chamber supplied with secondary air and an afterburning chamber with tangential outlet. Supply of secondary air directly into the combustion chamber, however, in order to secure an adequately effective reaction zone, requires a correspondingly large size of reactor, while the partition may give rise to unwanted flow resistance and increased backpressure, with possible resulting loss of engine output. Furthermore, the reaction, taking place especially at the partition owing to the impinging flow of exhaust, may impair its long-term durability.